1. Field of the Invention
The present invention relates to a gas turbine group. It also relates to a method for operating a gas turbine group.
2. Discussion of Background
A gas turbine group, which consists essentially of a compressor group, of a first combustion chamber located downstream of the compressor group and upstream of a first turbine and of a second combustion chamber acting downstream of the first turbine and upstream of a second turbine, is disclosed, for example, by German Offenlegungsschrift 27 02 440. In this gas turbine group and in the installations of similar arrangement which have previously become known, the combustion chambers are respectively configured as upright combustion chambers. The connections between a combustion chamber and the turbomachines located upstream and downstream are made by conduits, as is shown and described in the publication quoted, in some cases using inlet and outlet ducts which are difficult to design from aerodynamic and thermal aspects. Apart from the fact that the upright combustion chambers quoted, which generally rise at right angles to the rotor shaft, affect the size of the buildings, the axial space requirement for the inlet and outlet ducts necessarily involves a lengthening of the rotor shaft in such a way that, from static and dynamic considerations, the turbomachines then have to be supported in at least three bearings, the rotor shaft is subdivided between the individual turbomachines by couplings or the turbomachines are effectively connected to one another in a multi-shaft arrangement. Particularly in the case of jet engine gas turbine groups, as is apparent for example from German Offenlegungsschrift 34 47 717, the transition has been made by configuring the single combustion chamber between the compressor and the turbine as a so-called annular combustion chamber, which intrinsically permits a more compact external envelope of the complete turbine group. Where this technique is transferred to power station installations, however, the same problems, mentioned above, arise with respect to static and dynamic imponderables.